Tool Calls Can Fake Success: Paper Quantifies Agent Failure Modes

silentw111 · reddit · 2026-08-21

A new paper highlights that "tool success" and "actual effect" are often decoupled in agent systems. It identifies four failure modes like delayed visibility and partial success. Experiments show that adding independent postcondition verification boosted success rates from 64% to 100% and cut duplicate side effects from 72% to 20% under high fault conditions, emphasizing the need to verify effects, not just response codes.

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